Merge "Add support for missing public / private key files for apexes." am:...

Merge "Add support for missing public / private key files for apexes." am: babb1337 am: d2344eea

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2586953



Change-Id: I7e627429f9d0a83c0c977afecc7993da1ac689a2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>